Laryngeal masks, illustratively of the varieties disclosed in U.S. Pat. Nos. 4,509,514 and 4,995,388, are artificial airway devices designed to facilitate lung ventilation in an unconscious patent by forming a low-pressure seal around the laryngeal inlet. An inflatable-ring seal surrounds an appropriately shaped mask which fits into the lower pharynx and is attached to a tube which emerges from the mouth, as for connection to medical gas supply tubing.
In practice, these devices have been successful and are in daily use in hospitals throughout the United Kingdom. Such masks have been found to be effective in achieving a reliable airway, preventing obstruction in an unconscious patent. As presently used, such masks are especially effective in cases where difficulty with the airway is experienced. For example, the mask has been found to prevent contamination of the lungs by blood or debris following surgery of the nose and throat. But it has become apparent that an important contraindication to its use is the patient who is at risk from vomiting or regurgitation of stomach contents while unconscious. Said U.S. application Ser. No. 07/952,586 deals with this problem by providing an evacuation tube which is open through the center of the distal end of the inflatable seal of the laryngeal mask, thus utilizing the distal end of the inflatable ring as an inflatable cuff formation which establishes peripherally sealed engagement to the upper sphinctral region of the oesophagus and centrally supports the distal end of the evacuation tube. In addition, said U.S. patent application Ser. No. 07/952,586 discloses an additional inflatable cuff carried by the laryngeal mask and by the evacuation tube, for referencing inflation against the back wall of the pharynx, thus making it possible to establish the laryngeal-inlet seal with reduced inflation pressure, as compared with prior structures not having such an additional inflatable cuff.
Said U.S. patent application Ser. No. 08/003,900 is concerned with moulding techniques for manufacture of a variety of laryngeal masks; and, in conjunction with one of these, an inflatable back cushion is disclosed whereby the referencing inflation against the back wall of the pharynx is widely distributed, over substantially the full area of the laryngeal mask. Such a back-cushion construction has been found to be mechanically simple and highly effective, and it is desired to specifically disclose and claim the inflatable cushion in the context of each of several representative constructions, illustratively taken from the disclosures of said U.S. patent application Ser. No. 08/003,900.